Evaluation of crude glycerine inclusion in beef cattle diet: apparent nutrient digestibility and microbial protein synthesis

Crude glycerine (CG) is an abundant biodiesel byproduct and an alternative material for livestock diets. The objective of this study was to evaluate the effects of glycerol supplementation on the digestibility and microbial protein synthesis in Nelore steers. Five ruminally cannulated Nelore breed steers (522±43 kg) were used in a replicated 5×5 Latin Square design to evaluate 0 (control), 3, 6, 9 and 12% of CG in total dry matter of diets during five experimental periods of 21 days. The dry matter intake (DMI), ruminal apparent digestibility (RAD), intestinal apparent digestibility (IAD), total apparent digestibility coefficient (TAD) of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and non-fiber carbohydrates (NFC) were not affected (P > 0,05) by CG inclusion. Fecal flow of ether extract (EE) decreased linearly (P < 0.05) as the level of CG in the diet increased. However, the CDI and CDT of EE increased linearly (P < 0.05) as the level of CG in the diet increased. The inclusion of different levels of CG in the diet showed no significant (P > 0.05) effect on microbial protein synthesis. It is concluded that CG may be used in the diet of beef cattle up to 12% and can be considered a good alternative energy.